Exploring Composite Supernova Remnants: Fermi Studies on Evolution of Pulsar Wind Nebula Emission

1. Fermi Studies of Collaborators: D. Castro S. Funk Y. Uchiyama J. D. Gelfand O. C. de Jager A. Lemiere M. Lemoine-Goumard Composite Supernova Remnants

2. Evolution of PWN Emission • Spin-down power is injected into the • PWN at a time-dependent rate • Assume power law input spectrum: • - note that studies of Crab and other • PWNe suggest that there may be • multiple components 1000 yr 2000 yr 5000 yr • Get associated synchrotron and IC emission from electron population in the • evolved nebula • - combined information on observed spectrum and system size provide • constraints on underlying structure and evolution CMB inverse Compton synchrotron

3. HESS J1640-465 Lemiere et al. 2009 LAT 1 yr sensitivity • Extended source identified in HESS GPS • - no known pulsar associated with source • - may be associated with SNR G338.3-0.0 • XMM observations (Funk et al. 2007) identify extended X-ray PWN • Chandra observations (Lemiere et al. 2009) reveal neutron star within extended nebula • - Lx ∼1033.1 erg s-1 Ė ~ 1036.7 erg s-1 • - X-ray and TeV spectrum well-described by leptonic model with B ∼6 μG and t ∼15 kyr • - example of late-phase of PWN evolution: X-ray faint, but g-ray bright

4. HESS J1640-465 • Extended source identified in HESS GPS • - no known pulsar associated with source • - may be associated with SNR G338.3-0.0 • XMM observations (Funk et al. 2007) identify extended X-ray PWN • Chandra observations (Lemiere et al. 2009) reveal neutron star within extended nebula • - Lx ∼1033.1 erg s-1 Ė ~ 1036.7 erg s-1 • - X-ray and TeV spectrum well-described by leptonic model with B ∼6 μG and t ∼15 kyr • - example of late-phase of PWN evolution: X-ray faint, but g-ray bright • Fermi LAT reveals emission associated with source Slane et al. 2010

5. HESS J1640-465 • PWN model with evolved power • law electron spectrum fits X-ray • and TeV emission • - Fermi emission falls well above • model Slane et al. 2010

6. HESS J1640-465 • PWN model with evolved power • law electron spectrum fits X-ray • and TeV emission • - Fermi emission falls well above • model • Modifying low-energy electron • spectrum by adding Maxwellian • produces GeV emission through • inverse Compton scattering • - primary contribution is from IR • from dust (similar to Vela X) • - mean energy (g∼105) and fraction • in power law (∼4%) consistent w/ • particle acceleration models Slane et al. 2010

7. HESS J1640-465 • PWN model with evolved power • law electron spectrum fits X-ray • and TeV emission • - Fermi emission falls well above • model • Modifying low-energy electron • spectrum by adding Maxwellian • produces GeV emission through • inverse Compton scattering • - primary contribution is from IR • from dust (similar to Vela X) • - mean energy (g∼105) and fraction • in power law (∼4%) consistent w/ • particle acceleration models • GeV emission can also be fit w/ • pion model • - requires n0 > 100 cm-3, too large • for G338.3-0.3 Slane et al. 2010

8. G327.1-1.1: More (Reverse) Shocking Results • G327.1-1.1 is a composite SNR • for which radio morphology • suggests PWN/RS interaction • Chandra observations show • an offset compact source w/ • trail of nonthermal emission • extending back to radio PWN • - compact source is extended • and embedded in bowshock- • structure • - prong-like structures extend • from source, inflating bubble • in region cleared out by RS Temim et al. 2009

9. G327.1-1.1: More (Reverse) Shocking Results • G327.1-1.1 is a composite SNR • for which radio morphology • suggests PWN/RS interaction • Chandra observations show • an offset compact source w/ • trail of nonthermal emission • extending back to radio PWN • - compact source is extended • and embedded in bowshock- • structure • - prong-like structures extend • from source, inflating bubble • in region cleared out by RS Temim et al. 2009

10. Probing Composite SNRs With Fermi • G327.1-1.1 is a composite SNR • for which radio morphology • suggests PWN/RS interaction • Chandra observations show • an offset compact source w/ • trail of nonthermal emission • extending back to radio PWN • - compact source is extended • and embedded in bowshock- • structure • - prong-like structures extend • from source, inflating bubble • in region cleared out by RS • Good candidate for g-rays, • And…

11. Probing Composite SNRs With Fermi • Weak, but maybe a detection.

12. Probing Composite SNRs With Fermi 1FGL J1552.4-5609 • But what about this one?

13. Probing Composite SNRs With Fermi 1FGL J1552.4-5609 • Watch for studies of these and other such systems with Fermi

14. Conclusions • Gamma-ray emission provides • important information about • PWN particles that are difficult • to probe at other wavelengths • Observations of HESS J1640-465 • appear to require an additional • low-energy electron component • - may be a thermal peak, but • could be a distinct spatial • component as well • Other evolved PWN are good • candidates for Fermi studies, • and may reveal new information • on reverse-shock interactions • and underlying particle • distributions